1. Field of Invention
This invention pertains to the art of apparatuses for holding down containers or drums, and more specifically to an apparatus mounted on the top side of a base plate and engageable with a drum supported upon the base plate to hold down the drum while a platen assembly, for pumping molten thermoplastic material, is removed from the drum.
2. Description of the Related Art
It is known in the art to use various apparatuses to hold down a drum while a platen assembly is removed from the drum. Some of these apparatuses consisted of a pair of hold-down plates or pins. The hold-down plates were attached by a mechanism which included bolts sliding against springs which were attached to mounting plates which in turn were mounted to a base plate secured to the ground. The drum was placed between the hold-down plates and the lower surfaces of the hold-down plates engaged the flange that circled the bottom of the drum. The hold-down plates prevented the drum from being lifted along with the platen assembly while the platen assembly was being removed from the drum. However, this type apparatus had deficiencies. The force applied to the hold-down plates by the drum flange as the platen assembly was being lifted often caused the hold-down plates to be displaced from their proper position. The tendency of the hold-down plates to be displaced was exacerbated by the wearing of slots through which the bolts would slide. When the hold-down plates were displaced, they could puncture the base of the drum, thereby releasing the vacuum being created inside the drum due to the removal of the platen assembly. Puncturing the drum prevents it from being reused and causes it to be scrapped.
Applicant recognized a need to improve the existing hold-down mechanism to prevent the hold-down plates from being displaced and damaging the drum. Applicant also recognized the need to develop a hold-down mechanism which would not damage the platen seals during inadvertent or accidental downward movement of the platen assembly when a drum was not mounted under the assembly and on the hold-down plates. To that end, a chamfer has been included on the hold-down mechanism to provide a smooth transition for the platen seals as the platen assembly is lowered past the hold-down mechanism.
The present invention contemplates a new and improved hold-down mechanism for use with an apparatus for melting and dispensing solid thermoplastic material directly from a drum. The invention is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results.